Means for melting and molding materials



July 6, 1937. E. G. TOUCEDA El AL 2,086,483

MEANS FOR MELTING AND MOLDING MATERIALS Ham/a CT 777%.

T air" Attorney.

July 6, 1937. TOUCEDA r AL 2,086,483

MEANS FOR MELTING AND MOLDING MATERIALS Filed .Nov. 20, 1933 2 Sheets-Sheet 2 Eflf/que G. 751166022, Harv/a C 772 7}.

by wx The/r Aito'me Patented July 6, 1937 PATENT" OFFICE MEANS FOR MELTING AND MOLDING MATERIALS Enrique G. Touceda and Harold C. Tiflt, Albany,

N. Y., assignors to Consolidated Car Heating Company, Inc., Albany, N. Y., a corporation of New York,

' Application November 20, 1933, Serial No. 698,766

4 Claims.

Our invention relates to means for and to methods of melting, by the use of electricity, materials of various sorts having high melting points such as tungsten, platinum, gold, chromium,

5 molybdenum, manganese, tantalum and their alloys, as Well as quartz and clays, such as those used in the fictile arts and in the field of ceramics, and the like; and it also relates to means for and to methods of casting from such molten ma- 10 terials, of various sorts. Our invention is especially adapted for casting dental accessories including inlays, crowns, fixed bridge work, partial or full restorations and the like, our invention is especially adapted for melting'the ma- 15 terials indicated, in a crucible and casting the same inan adjoining mold both forming a unit on a centrifugal machine and for projecting the molten material directly from the crucible into the molds by centrifugal force, an operation that,

as far as we are aware, has never before been achieved nothwithstanding a long felt desire by those versed in this art, for the possibility of such achievement.

The foregoing andother objects of our in- 35 vention will be understood in detail from the following description of the principles and methods involved, ofthe elements of said means, and of their arrangements and modes of operation, reference being had to the accompanying drawings,

30 in which:-

Fig. l is a view in side elevation of one form of device of our invention showing a horizontal arm and a spring motor for spinning said arm about a vertical axis, which arm carries with it 35 a mold flask on one side of said axis, a counter-' weight on the opposite side and a crucible adjoining, said crucible being connected in an electric circuit over which current is supplied for directly heating the crucible. In this figure a por- 40' tion of the rame of the motoris broken away for illustration and both the crucible and the fiask are shown in section.

Fig. 2 is a plan view of. the spring motor. In f this figure the cap of the motor is omitted, as well as all parts of the device of Fig. 1 above line '2-2. r

Fig. 3 is a plan view of the device of Fig. 1 with the counterweight side of the horizontal 5 arm broken away.

Fig.'4is a view similar to Fig. 1 showing an electric motor, for spinning the horizontal arm,

substituted for the spring motor. In this figure the circuit to the crucible, over which the heat- 55 mg current is supplied to the crucible is completed through suitable collector rings on the shaft of the motor.

Fig. shows the left portion of the rotating arm of Fig. 1, and a modified form of crucible in side elevation.

- 5 Fig. 6 is a similar drawing to that of Fig. 5 showing still another form of crucible.

Fig. l is a plan view of the same portion of. the apparatus as that shown in Figs. 5 and 6 with still another form. of crucible, the longitudinal 10 axis of which latter is placed at about sixty degrees with that of the rotating arm, to whichlatter the crucible is attached by a bracket device, a portion of which is shown in Fig. 8, which bracket comprises a pair of auxiliary parallel arms clamped by a thumb bolt to a combined clamp and holder, a portion of which is shown in Fig. 8. Y

Fig. 8 is an end view in elevation of the rotating arm of Fig. 7, as viewed from right to left, showing a portion of the clamp and holder 7 of Fig. '71. I

Fig. 9 is a view in perspective of one form of combined crucible holder and electric terminal.

Referring now more indetail to the drawings the invention comprises a motor of any suitable type, such as a spring motor A, Figs. 1, 2, and 3, or an electric motor B, Fig. 4.

The spring motor may be of. the usual type such as a phonograph spring motor, which as shown comprising a frame 2 with a transverse head or platform 3, in the center of which there is provided a well, extending along the longitudinal axis of the motor, which well receives a short shaft 4 attached to the inner end of a coiled spring Y, the outer end of which spring is anchored to the frame 2.

The motor frame is provided with a cap 5, having a ball bearingfi, through which a stud shaft 1 extends, the lower portion ,8 of which, being comparatively small in diameter, extends into a central bore 9 of small'diameter in the shaft 4, along the longitudinal axis, that is, the

II and I2, each having its longitudinal axis in a cylindrical surface generated about the said axis of rotation of shafts 4 and 1, parallel to said axis of rotation. Each of these pins has its top end wedge shaped, each wedge having a face sloping across its longitudinal axismentioned. 56

said faces of said pins facing in a. clockwise direction along a circle in said cylinder perpendicular to said axis of rotation. The stud shaft 1, on the other hand, is provided with a pin l3 on the lower end in operative relation to said pins II and I2, the central axis of, which pin extends parallel to the'said axis of rotation of shaft 1 in said cylinder. This ,pin i3 has a cushion spring s behind it, normally pressing said pin downwardly into the path of rotation of pins I i and I2.

The top shaft 1 is slotted transversely as indicated in Fig. 3, to receive the arm l4, which arm is secured in said slot by a nut l5 and set screw I6. When thus secured to said shaft, arm l4 may be used to wind the motor spring Y, manually. This may be done by rotating arm I4 clockwise, Fig. 3, whereupon shaft 1 will belikewise rotated, causing pin I3 to engage one of the pins H or l2, and causing also the like rotation of shaft 4. When the spring Y has been sufficien tly .wound, a rod II, (which is vertically mounted in the frame of the motor, to slide up or down, and which may be manually operated up or down by the lever-i8 attached to the lower end thereof, as shown in Fig. 3,) is raised into the path of rotation of said arm l4, to hold themotor arm I4 in its wound condition, until it is desired to. release said arm, to spin the same about the axis of rotation of shaft 1 by the motor spring, as for example, when a casting is to be made. When it is decided so to spin said motor arm, the lever I8 is depressed 'pass over the slanting faces of the pins II and [2, due to the action of the cushion spring s as long as the counterclockwise rotation of the arm continues.

At the left end of the motor arm l4 there is securely attached thereto a flange H! which projects upward, as in Fig. 1. Further along the same arm toward the right there'is another flange 20 also securely attached to said arm as shown in the same figure. The flange i9 is provided with a thumb screw 43, the longitudinal axis of which lies parallel to the longitudinal axis of the arm [4. Opposite said thumb screw the flange 20 has a circular aperture 2| about a horizontal axis which latter is an extension of the longitudinal axis of said screw, and behind the flange 20, that is to the right thereof, we provide a platform 22 for supporting the crucible C, which platform is also secured to the arm l4. This platform is indicated as being metallic, but

' it may be made of nonconducting material if desired. When saidplatform is made of metal, it is covered with a plate 23 of insulating material thereby insulating the crucible from the frame of the device. Said plate may be secured to said platform, for example, by means of screws 24. See Fig. 3.

The crucible C is preferably held in place by electric terminal holders 25 and 26. Each of these holders, 25 and 26, has a base section a and b respectively, see Figure '4, and a corresponding cover section 0 and'ii. respectively, the cover 0 being hinged to the base a and the cover d being hinged to the base 2). Each base a and b is secured to the plate 23 in any suitable manner, as for example, in the manner indicated in Fig. 9, where the elements generally designated e and f, are secured to the plate 34 of insulation material (corresponding to plate 23,) by screws 35. For locking the cover elements 0 and d to their base elements, we provide screws 28 and thumb nuts 29, as in Fig. 4, or 30 and 3|, as in Fig. 9.

The crucible C of Fig. lconsists of a carborundum body, having, preferably, enlarged terminal heads 32 and 33 and a comparatively restricted hollow body section between said heads. Also preferably the restricted portion is covered with a heatinsulating material 34 such as asbestos. The left end of the crucible extends out to form a nozzle 36 which projects into the aperture 2! in the flange 20. This nozzle has an outlet duct 31 which connects through head 33, with the cavity 38 in the hollow body of the crucible, as shown in Fig. 1. that is the right end of the crucible, has an inlet aperture that is provided with a removable plug 39, said aperture communicating through the other head 32 with the cavity 38, said aperture serving as an inlet for charging the cavity of said crucible with any material that is to be melted therein. The inside of the cavity 38 may be lined with a suitable refractory material in the form, for example, of a tube 40 separate from the crucible and removable therefrom by way of the outlet terminal on the right, which is normally closed by plug 39. However, the inner side ofjthe crucible may be permanently lined. As a lining, we prefer to use alundum, quartz,'magnesia, crome cement, and the like.

When it is desired to cast a mold of any of the metals mentioned or their alloys or of any of the other of said materials mentioned, the plug 39 is removed from the inlet and a pellet or charge 4| of such metal or material is inserted in the crucible by way of said inlet after which the plug is restored. Thereafter the terminals of any suitable source of current, such as a battery or generator, are applied to said termi- The opposite end;

nals 25 and 26, as for example, under the thumb nuts 29, thus setting up a current circuit through the crucible by way of said terminals 25 and 26.

In this circuit, in series with the crucible, we insert an ammeter 42'. It will be found that when a constant potential is maintained at the current source the current flow through the crucible will rise as the temperature in the crucible rises and with a given size of pellet or charge 4|, of a given metal, such pellet or charge will melt when a given current flow is indicated in the ammeter. Therefore, the current reading at the ammeter may be used as an index of such temperature and as an indication of the physical condition of the pellet of charge, that is whether it is molten or solid. The ammeter will indicate when the desired crucible temperature has been attained. and therefore indirectly when the metal is molten and in proper condition to be cast. at which point the current is cut 011 from the crucible and the casting operation initiated, thus ensuring against overheating the charge. This arrangement therefore enables us to use a closed crucible, which we do in order to exclude the air from the crucible chamber when the crucible 4 becomes heated thus preventing any chemical action with oxygen. Even in the type of crucible of Figure (i the air is practically excluded by way of the outlet duct, as soon as the temperature begins to rise to any considerable degree, for all ordinary purposes.

In order to prevent the molten metal from spilling out of the duct 31, until the time of casting, the axis of the duct is elevated above theaxis'of the cavity 38 as much as possible and as indicated in Fig. 1.

When it is desired to produce a casting from the molten metal or other material, a suitable mold, such as mold 42 Fig. l, is clamped between the flanges l9 and 20, by means of the thumb bolt 43, with the port 44 of the mold opposite the opening 2| in the flange 20, as indicated in Fig. l. The port 44 is connected by suitable ducts, such as duct 45, with cavities in the mold. The apparatus being thus lined up, the spring of the motor having been wound up as previously described, and locked by rod I1, and the metal having been inserted in the crucible, the current is turned on until the ammeter gives the proper indication; whereupon the lever I8 is pressed down to release the arm l4, whereupon the spring F spins the arm I4 with its crucible and mold thereon. The centrifugal force set up by the rotation of the arm shoots the molten metal through the duct 31 across the space 44 into the. duct or ducts 45 and finally into the depths of the cavity or cavities in the mold producing the casting desired,

It will be understood that crucibles of different types, as indicated in the drawings, may be used and also different sizes of each type, depending upon the size and nature of the object to be cast.

Referring to Fig. 5, crucible 46, is a modification of the one shown in' Fig. 1, in that it has, in addition to the outlet duct on the left and the inlet aperture on the right (both as in Fig. 1) on the top side under the plug 41 another aperture for inspection of the crucible cavity, as for example, to determine if it is charged, before a melting operation is started. The plug 41, which may be made of carbon or of any suitable refractory material, such as quartz, andthe'like is made with a flange cap 48 curved on the under side to conform to the curvature of the outer surface of the crucible and is seated thereon as indicated in Fig. 5. The tube lining 49 is also correspondingly perforated, the two perforations, the one in the side of the crucible and the one-in the lining, being in alinement, in order that the crucible may be examined by removing the plug 41. Or, if quartz is used, for the plug, the examination may be made through the plug itself without its being raised. In Fig. 5, for convenience, the heat insulating material, corresponding 0 t xwcan be more effectively controlled. The proterial 34 in Fig. 1, has been omitted. Otherwise v the device of Fig. 5 is the same, as that of Fig. 1.

Referring to Fig. 6, the crucible 5| is made in the shape of a cup with anupper opening through which the crucible is charged, which opening is kept closed by a cover 54. It also has a lining 52, also in the shape of a cup. The outlet duct 53 normally stands above the molten material to prevent the latter, from running out of duct 53 under the force of gravity but when the crucible is spun the centr fugal force produced carries the molten material oward the left side piling it up above the port 0 ening of the outlet duct 53 and forcing it out through the outlet. The crucible cover 54 may be secured in place in any suitable mannerto maintain the crucible chamber closed after thecharge has been put in the chamber. This crucible and its cover are made of the same material as the crucible of Fig.1, and the electrode terminals 55 and 55 for conveying the ourrent to the crucible are preferably located on the outside of the cup as shown in the figure. These electrodes may be in the shape of plane copper rings which tightly fit the outside of the cup and which may also be held in place by the heat insulating jacket 51. Otherwise the mechanism is substantially the same as that in Figs. 1 and 5. The cover 54 may be made of the same material as plug 41, Fig. 5.

Referring to Fig. 7, the crucible 58 is the same as that in Fig. 1 except that the outlet duct 59 is inclined at about 60, more or less, to the longitudinal axis of the crucible. Consequently, the crucible itself, has to be shifted to the same extent about a vertical axis crossing the longitudinal axis .of the arm 68, (which latter corresponds to the arms 84 in Figs. 1, 3, 4, 5, and 6) to line up with port of the mold 6i which latter corresponds to the mold 42 in Figs. 1, 3, 4, 5, and 6, but the port 60 of which is smaller than port 44. In the device of Fig. 7, the upper left hand corner of the crucible is chamfered tofit the face of the mold (the flange 20 of Figs, 1, 3, 4, 5, and 6 being omitted) so that the mold may be clamped, as shown directly against the face of the crucible 58, which crucible, is clamped .in turn between arms 82 and 53 bya=--thurnb bolt 64, said arm being secured to a bar BF that has extension arms 66 slotted to receive and to facilitate its being secured to arm 68 by screw 61. be understood that the arm 68 corresponds to arm l4 in the other figures, except for the omission of the flange 20 and of the platform 22 and for the substitution of the supporting element 66, (a section of which is shown in Fig. 8) for platform 22. 7

It will be understood that the crucible of Fig. 6 may be heated also by a high frequency coil or energized by either the frequency coil or by the application of current from a current source as previously described. When a high frequency coil is to be used the opencoil of the latter will have to be large enough to permit the high frequency coil being slid into place around the crucible where it is helduntil the material in the crucible is melted. The coil is then lifted to permit the crucible and mold to be spun as a unit to drive the molten charge into the mold.

Another advantage in using a closed crucible and bringing the crucible outlet port and the mold outlet port into alinement, as in Fig. 1, to form a conduit, through which the molten material may be shot straight through into the mold, is that the thermal conditions of the charge vision of the lining also makes it possible (when a carbon crucible is used and when a charge is to be melted which will absorb carbon) to prevent the carbon from being absorbed by such a charge. However, when materials that have no affinity for carbon are used as a charge for the crucible the lining may be omitted.

Instead of the terminals of Fig. 9 for the crucible the flange 20, Fig. 5, may be insulated from the arm l4 and a duplicate of flange l9 may be appliedto the arm l4, on the opposite side of the crucible 45, and insulated also from-arm I4, with the screw 43 reversed, that is with the terminal 10 that engages the metal head 1| of the mold 42, Fig. 5, on the left, and t e head of this screw on the right side of the fla ge, in order that the crucible 46 may be clampe between the flange 20 and the screw'43. The flange 22 may then be omitted. Preferably a metal plate similar to head II, but approximating in size the enlarged It will screw plate, may be interposed between the screw and the crucible, just as the head H is interposed between the mold and the screw in Fig. 5. Also, if desired, a graphite block may be interposed at one end between the crucible and the flange 2ll-and on the opposite end between the crucible and plate engaged by the screw. With this arrangement the flanges may be used as electrode terminals, each having a binding postto which one of the leads from the current source may be attached. With this arrangement, the crucible is charged before it is clamped between the insulated flanges. After being charged it is located against the insulated flange 20 with the duct 12 in alinement with the opening 13 in the flange 20 and with the port I4 leading to the mold inlet duct 15. The screw plate is then applied to the right end of the crucible and the screw turned until the crucible is caught and held between the screw plate and the insulated flange 20. After the crucible is thus clamped current may be applied through the crucible by way of the insulated supporting flanges. If desired, the port'M may be made smaller, for example, of a size the same as the port 60 of Fig. 7 and the opening 13 of the same size. The face of the crucible will then set against the face of the flange somewhat as it is set against the face of the mold in Fig. 7, except that in Fig. '7, the chamfered portion engages the face of the mold.

We also contemplate, when the crucible is thus supported, substituting a crucible without the enlarged heads, attaching graphite plates to the faces of the insulated supporting flange 20 and of the screw plate next to the crucible which crucible instead of engaging the flange 20 and screw plate directly will engage the graphite plates as electrodes instead, the insulated flanges, the screw and screw plate, the graphite plates and the crucible, being in a series circuit with the source of current.

It will be understood that our invention is of broad application, that while for the purposes of illustration we have described specific means and application of the principles involved, we do not wish to be so limited since such application and .means may be modified or varied without departing from the principles involved.

For example we contemplate another form of construction in which we omit the plug 41 of Fig. 5 and having the crucibles slotted from one head 16 to the other '11, the slot being just wide enough to permit the lining tube 18, (corresponding to lining tube 40) being dropped in place between saidv heads, the tube in this case being closed from one end tothe other as tube 40 of Fig. 1. This modification can also be used in the form of device described, in which the insulated flanges, the screw plate andthe crucible between said plates are connected in series with the source of current. With this arrangement the lining tube is first charged and then dropped in place in the slot between said plates, the end openings of the tube being suificiently closed by said plates, the head plates, to keep the air out.

What we claim is:-

1. A crucible comprising a body of carborun-- dum having a pair of terminal heads and having an internal cavity located between said heads, an opening in said crucible leading to said cavity whereby said cavity may be charged therethrough, a cross section of said body across said cavity enclosing a smaller area than a cross section of head of the crucible, to which we will refer as the either of said heads taken parallel to said cross section of the body, whereby when electric terminals are applied to said heads and a flow of current is caused to pass through said body between said heads by way of said terminals and the temperature of said body is raised sufllciently to melt the charge, the said heads are maintained comparatively cool.

2. A crucible comprising an integral body of carborundum having a pair of terminal heads and having an internal cavity located between'said heads, an opening in said crucible leading to said cavity whereby said cavity may be charged therethrough, a cross section of said body across said cavity enclosing a smaller area than a cross section of either of said heads taken parallel to said cross section of the body, whereby when electric terminals are applied to said heads and a flow of current is caused to pass through said body between said heads by way of said terminals and the temperature of said body is raised sufficiently to melt the charge, the said heads are maintained comparatively cool, and a duct extending through one of said heads and connecting with said cavity through which latter the molten charge'may be forced out of said cavity, the port of said duct in the cavity being located substantially above the lower level of the cavity whereby the molten charge is prevented from being forced out of the duct by gravity.

3. A crucible comprising an integral body of carborundum having a pair of terminal heads and having an internal cavity located between said heads, an opening in said crucible leading to said cavity whereby said cavity may be charged therethrough, across section of said body, across said cavity enclosing a smaller area than a cross section of either of said heads taken parallel to said cross section of the body, whereby when electric terminals are applied to said heads and a flow of current is caused to pass through said body between said heads by way of said terminals and the temperature of said body is raised sufliciently to melt the charge, the said heads are maintained comparatively cool, a duct extending through one of said heads and connecting with said cavity through which latter the molten charge may be forced out of said cavity, a refractory lining in said cavity interposed between the charge and the cavity walls, the port of said duct in the cavity being located along the upper inside level of the lining, whereby the molten charge is prevented from being forced out of the duct by gravity.

4. A centrifugal casting machine of the class having a mold flask element and a crucible elechange of resistance in said negative resistance crucible member accompanying attainment of the critical fusion point by the material being heated, a signal of an attention arresting character is provided by said indicator for the guidance of the operator in applying said casting moment.

ENRIQUE G. TOUCEDA. HAROLD C. TIFFT. 

